I’m just wondering why people keep buying these engines? Or a boat with an optimax in them? I live in Alaska born and raised here. I think there is a lot of people confused up here and they keep buying like SJXs and Phantons for no good reason at all. I’m just wondering if anybody can explain this nonsense that I’ve been experiencing through the years.

Power to weight ratio. Shallow water ability. Inboard pump efficiency. Can haul a pretty good load. Pretty much on step in a boat length. Decent fuel consumption if you aren't constantly hammering on it. Only negative as far as I'm concerned is you lose some floor space compared to an outboard.

Yentna_WWS_LS3 wrote: I’m just wondering if anybody can explain this nonsense that I’ve been experiencing through the years.

It's about as close as one can get with having a lighter weight boat with reputable power (190 +/- at the nozzle) and haul some sort of a decent load and yet have shallow water capabilities as an outboard jet. There's obvious pluses and minuses that come along with boats like these, but those who have them, typically love them for what they do for their particular applications.And noise has always been one of the minuses....

Yentna_WWS_LS3 wrote:I’m just wondering why people keep buying these engines? Or a boat with an optimax in them? I live in Alaska born and raised here. I think there is a lot of people confused up here and they keep buying like SJXs and Phantons for no good reason at all. I’m just wondering if anybody can explain this nonsense that I’ve been experiencing through the years.

Why don't you tell us why you are so dead set against them? Are you referring to inboard jets only? What would you use in their place?

I understand Mercury is doing away with the optimax do to pollution requirements.I just saw a Hewescraft sportjet with a Rotex 3 cylinder supercharged motor 140 hp. about the same weight and half the size. Talk about a win,win

They seem to be very unreliable for people that put serious hours on their boats. The inboard jet unit has reverse cup issues as well. I’ve known quite a few people that had many issues with them. I see them getting towed down the river a few times a summer. Possibly just because they are so common. A Two stroke high pressure direct inject outboard designed powerhead converted into an inboard just doest seem like it would be the most reliable. Wouldn’t a v8 GM engine be more reliable?

Yentna_WWS_LS3 wrote:They seem to be very unreliable for people that put serious hours on their boats. The inboard jet unit has reverse cup issues as well. I’ve known quite a few people that had many issues with them. I see them getting towed down the river a few times a summer. Possibly just because they are so common. A Two stroke high pressure direct inject outboard designed powerhead converted into an inboard just doest seem like it would be the most reliable. Wouldn’t a v8 GM engine be more reliable?

This must be why you bought a WWS with an LS3? Strange first 2 posts. Which pump did you go with? Maybe you can tell us why you choose it over the others?

Yentna_WWS_LS3 wrote:They seem to be very unreliable for people that put serious hours on their boats. The inboard jet unit has reverse cup issues as well. I’ve known quite a few people that had many issues with them. I see them getting towed down the river a few times a summer. Possibly just because they are so common. A Two stroke high pressure direct inject outboard designed powerhead converted into an inboard just doest seem like it would be the most reliable. Wouldn’t a v8 GM engine be more reliable?

Sport jets are plenty reliable. Other than the fuel lift pump failures which are well known and easily addressed by carrying a spare there are no consistent mechanical problems. I don't think they break down any more often than any other engine.

A gm v8 at 3x the weight is not a viable replacement for many of the small boats you find a sj in.

Well why do some people buy ford 6.0l's when they are known to have problems? Because they can and its their money. I'm not a fan of the sport jet but they have their place, if i couldn't have a v8 id have a sport jet and id be happy with it. And a v8 is not 3x the weight...

Oh come on I’m not trying to piss everyone off. I just see a lot of people spent 60K or more on some SJX or Phantom with a sport jet and I wonder why people wouldn’t spend the same money or maybe a little more on a weldcraft, customweld, or Thunderjet.....And a high pressure direct inject 2 stoke engine is not more reliable than a 4 stoke GM engine. I know people with over 3000 hours on their 8.1s and 454s. Excluding lemons they exist for sure. And my new boat has a 6.2 LS3 matched to a hami 212 with 3.4kw turbo impeller. Last year was a little slow for me and I only got to put just over 100 hours on it. So it’s still unproven. And opinions are like assholes everyone has them. Don’t get all pissy if we have different opinions. I’m a huge fan of center council stick steer in a Idaho style jet boat. I don’t think there is a better all around boat for Alaska. I just don’t see why people would spend so much money on an inboard Jon boat over an RMX 19 with a 350 and 212. Just an example.....

Yentna_WWS_LS3 wrote:Oh come on I’m not trying to piss everyone off. I just see a lot of people spent 60K or more on some SJX or Phantom with a sport jet and I wonder why people wouldn’t spend the same money or maybe a little more on a weldcraft, customweld, or Thunderjet.....And a high pressure direct inject 2 stoke engine is not more reliable than a 4 stoke GM engine. I know people with over 3000 hours on their 8.1s and 454s. Excluding lemons they exist for sure. And my new boat has a 6.2 LS3 matched to a hami 212 with 3.4kw turbo impeller. Last year was a little slow for me and I only got to put just over 100 hours on it. So it’s still unproven. And opinions are like assholes everyone has them. Don’t get all pissy if we have different opinions. I’m a huge fan of center council stick steer in a Idaho style jet boat. I don’t think there is a better all around boat for Alaska. I just don’t see why people would spend so much money on an inboard Jon boat over an RMX 19 with a 350 and 212. Just an example.....

Congratulations This is what your first post should have been without the Pissy part. I happen to agree with you. I would never have an out board or any derivative there of. I believe them to be unreliable and very expensive to fix.

Yentna_WWS_LS3 wrote:Oh come on I’m not trying to piss everyone off. I just see a lot of people spent 60K or more on some SJX or Phantom with a sport jet and I wonder why people wouldn’t spend the same money or maybe a little more on a weldcraft, customweld, or Thunderjet.....And a high pressure direct inject 2 stoke engine is not more reliable than a 4 stoke GM engine. I know people with over 3000 hours on their 8.1s and 454s. Excluding lemons they exist for sure. And my new boat has a 6.2 LS3 matched to a hami 212 with 3.4kw turbo impeller. Last year was a little slow for me and I only got to put just over 100 hours on it. So it’s still unproven. And opinions are like assholes everyone has them. Don’t get all pissy if we have different opinions. I’m a huge fan of center council stick steer in a Idaho style jet boat. I don’t think there is a better all around boat for Alaska. I just don’t see why people would spend so much money on an inboard Jon boat over an RMX 19 with a 350 and 212. Just an example.....

A little off topic: what boat you got? What kinda performance outta that combo?

Akclassic wrote:Well why do some people buy ford 6.0l's when they are known to have problems? Because they can and its their money. I'm not a fan of the sport jet but they have their place, if i couldn't have a v8 id have a sport jet and id be happy with it. And a v8 is not 3x the weight...

Engine, pump, manifolds, heat exchanger etc, +/- 3x the weight... Yes. I'm not suggesting a sj is better than the V8L, but it's apples to oranges. You just can't put 900 lbs at the back of a short shallow water boat without some serious downside.

The new boat I love. I ran my Thunderjet for 4 years and really figured out what works and what doesn’t on that boat. I settled on a slightly used 2010 custom weld whitewater. It’s 21 feet long, 9 foot beam 7 foot bottom. I run a marine power “GM” LS3 port fuel injected 6.2. Matched with the Hamilton 212 3.4kw impeller. Under a normal load around 1200lbs i found the sweet spot in the throttle. That’s about 3500rpms. It runs just over 30 mph up stream and about 38-40 down. And burns 12GPH. With the boat being so wide I can really back off the throttle and go slow on step. I would never buy another jet boat without stick steering. It is truly amazing. This boat is a 21ft jet ski. WOT is 4200-4100 rpm.

Dry weight of these engines is without pump.

Kodiak marine LS3 6.2 weighs 657lbs Sport jet weighs 367lbs. At least that’s what I got from their web sites. They probably all lie. Keep in mind also that mine is an aluminum block. A iron block 350 or 6.0 weighs more.

The sportjet weighs 367 lbs including the pump. They have their place in a shallow water, smaller boat. There is no way I could go where I do with a v-8 in my Tomcat. That being said even with mufflers my 250 sportjet is extremely loud. There is no perfect boat or motor and that is why I have more than one boat, one 17’ w/sportjet, and a big water boat with a Hamilton pump.

Do you guys think a welded John boat like a sea ark or something with a outboard 150 would fill the same shoes as a sport jet extreme shallow, SJX exc...? I do believe sea ark/Yamaha combo is cheaper. And a lot of people like them. Almost any inboard jet boat with an 11degree bottom or less will run on step in inches of water. The heavier v8 boats need tons of water to idle in though. Can these phantoms exc... idle in really shallow water without sucking trash? If so that would be an advantage.